I'd think she's younger than 16 (or equivalent in elven age) since even now you wouldn't tend to call a 16 year old a child, unless talking in legal terms. I mean, 16 year olds don't tend to be about 2/3 the height of an adult. They're more or less adult sized. She seemed more like she was meant to be the equivalent of 10 or so.
And to the OP - elves are traditionally taller than humans, it's just that DA was just reversing things to try to differentiate itself - so elves are small and live in slums rather than being tall and living in amazing magical cities. Wizards are imprisoned in towers and are on a very low social strata rather than lording it over everyone else from their own personal tower. And so on.
